An optically active epoxide which is useful for medical products, agricultural chemicals and synthetic intermediates thereof is known to cause a decrease in optical purity due to heating (Can. J. Chem. (1976), 54, 3364-76 and J. Chem. Soc., Perkin Trans. 1(1983), 3, 595-9, etc). In obtaining an optically active epoxide by distillation, the optical purity is decreased by heating for distillation. Particularly, in production on an industrial scale, the decrease in the optical purity causes significant adverse effects on yield, quality, and the like. Therefore, an obtaining method using a general-purpose distiller or rectifier accompanied with excessive heating is unsuitable for obtaining an optically active epoxide by industrial distillation or rectification, and the obtaining method is limited to thin-film distillation or the like, thereby limiting an improvement in quality of the optically active epoxide. A means for solving this problem has not yet been known.